“I’m afraid I may have damaged a really good record by using tap water to clean it, is there anyway to remove harsh tap water deposits?” – P.
A satisfactory answer to your question is a function of the availability of Distilled or De-ionized water. A gentle cleaning with a few drops of dish washing detergent dispersed in a soup bowl of luke warm Distilled water, using a very soft, natural bristle brush to apply the soapy solution. This is followed by a rinse of Distilled water. Then drying with a clean, lint free towel to completely remove all of the rinse water. This series of steps, could solubolize the tap water residue, flush it away, and then remove with absorbent towels any water residue.
Numerous users have claimed good results using a vacuum cleaning record cleaner such as a VPI, or Nitty Gritty machine.
The other possibility would be to gain access to a Ultra Sonic Cleaner designed for phonograph records.
You may have to experiment to determine the most effective process.
Sincerely, Walter Davies